Process for rectification of propane nitration stream

Abstract

It is the discovery of the present invention to provide an improved method of rectifying the crude production stream obtained by the vapor phase nitration of hydrocarbons by subjecting the absorber bottom mixture to extractive distillation with water.

We claim: 
     
       1. In a method for rectifying the crude production stream obtained from the process of vapor phase nitration of hydrocarbon to produce nitroalkanes, which includes passing the vapor phase nitration stream from a nitration chamber through a condenser to condense a substantial portion of the normally-liquid components and separate said normally-liquid components from normally-gaseous components, forming absorber bottoms by passing the gaseous components into a water absorber to wash the gas, said absorber bottoms including nitroalkanes, acetaldehyde, nitrogen, nitrogen oxides and oxygenated compounds, stripping the condenser liquid and absorber bottoms by distillation to form a condensate including a water layer and an oil layer, said oil layer comprising crude nitroalkanes and low boiling components, stripping the low boiling components from the condensate in a heads column, and fractionating the oil layer to produce fractions of nitroalkane components, the improvement comprising, subjecting the condenser liquid and absorber bottoms solely to extractive distillation with substantially pure water to remove sufficient impurities therefrom so that the condensate is relatively free of impurities, thereby avoiding carbonaceous build-up in the heads column and fractionater during extraction of the nitroalkanes. 
     
     
       2. The method of claim 1 wherein the water used for extraction is used in a volume of about 1 part of liquid to one part of nitroalkane vapors. 
     
     
       3. The method of claim 1 wherein the water used for extraction is used in a volume of about 2.5 parts of liquid to one part of nitroalkane vapors.